Thanks for all the responses. Fuel is fresh, not sure of cetane rating but I get it from a reputable supplier for off road fuel. Air cleaner is new. It's been like this for about 2 or 3 years. Like I said it seems to run OK, little low on power and hard to start cold. Even in the summer. Need to try trhe fuel conditioner. I wouldn't think there would be air in the fuel system, it's been 2 years since fuel filter was changed.